Sonic Forces is not a bad game, and the only thing dragging it from "pretty good" to "decent/passable" is the classic sonic stages, which yes are atrocious. Boost sonic is done serviceably (if not quite up to the Unleashed/Generations standard) and the avatar stages are a legitimately fun evolution that takes the wisp concept and turns it into some interesting mechanics
06 has the funny haha glitches to mess with but otherwise is just kind of disappointing. It's bad in the subtle ways that make it unfun, but not bad in the egregious ways that turn something into a camp classic, unlike what everyone thinks it's like from watching youtubers joke on it
Both versions of Lost World have a problem where the movement feels kind of stilted, especially when parkour gets involved, and it ends up feeling too manual without having the fun depth of many other sonic games' control schemes (and yes I'm counting 3D sonic here). I didn't really play either past the first couple of levels so I dunno if it gets more interesting later on
Forces is absolutely the most enjoyable out of the three, people just like to dunk on it because it came out right after Mania